

import matplotlib.pyplot as plt
import numpy as np

n = 12
X = np.arange(n)
Y1 = (1 - X / float(n)) * np.random.uniform(0.5, 1.0, n)
Y2 = (1 - X / float(n)) * np.random.uniform(0.5, 1.0, n)

plt.bar(X,Y1)
plt.bar(X,-Y2)

plt.xlim(-0.5,n)
plt.ylim(-1.25,1.25)

for x,y in zip(X,Y1):
    plt.text(x,y+0.05,'%.2f'%y,ha='center', va='bottom')

for x,y in zip(X,Y2):
    plt.text(x,-y-0.05,'%.2f'%y,ha='center', va='top')




plt.show()